Book/Report

FZJ-2018-03083

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Überprüfung der Eignung der Rauschthermometrie zur genauen in situ Kalibration von Thermoelementen in technischen Prozessen : Verifikation der erreichbaren Genauigkeit an Fixpunkten

Fechner, H. (Corresponding author)FZJ*

1988
Kernforschungsanlage Jülich, Verlag Jülich

Please use a persistent id in citations: http://hdl.handle.net/2128/18606

Report No.: Juel-2254

Abstract: Combined sensors (TC-NT) are normally used for noise temperature measurements carried out under industrial conditions where two thermocouples (TC) and a noise sensor (NT) are positioned in the sensor tip. The thermocouples in the combined TC-NT may be recalibrated in situ at any time via the noise sensor with relativeaccuracies of 0.1 - 0.5 %. The increased applications of noise thermometry to be expected in future for the precise in situ calibration of operational thermocouples in technical processes (e. g. in high-temperature reactors, coal gasification facilities, hot isostatic pressing, diffusion furnaces etc.) requires precise knowledge of the achievable accuracy of the noise thermometer's "temperature reading". This is particularly true since due to the further development of the electronic devices and the status already achieved in optimizing the signal transmission of measuring noise- spectra overall measuring accuracies in the range of about 5 - 10 10$^{-4}$ can be achieved. The aim of this study was to determine the achievable accuracy of the noise thermometer developed at the KFA in the range from 0 to 1000 $^\circ$C under laboratory conditions. "Under laboratory conditions" means, for instance, that the transmission lines can be kept very short so that their influence becomes negligibly small. To this end precision noise temperature measurements at fixed temperature points (triple point of water, freezing point of zinc, freezing point of silver) were carried out with the version of the further developed noise thermometer currently available (these are the same instruments used in various reactor experiments during their trial period). The fixed point technique and the conventional precision resistance thermometry, which is required to operate the fixed points, wereestablished in accordance with the requirements of accurate (and thus longer lasting) noise temperature measurements. The careful analysis of all possible sources of error ensured - hat all systematic or random errors were in the range of a few 10$^{-5}$. It is shown that the further developed KFA noise thermometers, which can be used under industrial conditions, achieve under laboratory conditions a measuring error of about $\pm$ 2.5 10$^{-4}$ - relative to the thermodynamic temperature scale - in the-temperature range from 273.16 K (0.01 $^\circ$C) to 1234.894 K (961.744 $^\circ$C). If, assuming that the individual measured values display a normal distribution, the noise measurements at the zinc and silver point are combined to a mean value then it becomes appargnt that the average noise temperatures only deviate by + 2 10$^{-5}$ (zinc) or + 4 10$^{-5}$ (silver) from the respective thermodynamic temperature. Noise thermometry therefore seems - as demonstrated by the results obtained - to make available an independent metrological method for the precise measurement of thermodynamic temperatures in theelevated temperature range.

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Contributing Institute(s):

1. Publikationen vor 2000 (PRE-2000)

Research Program(s):

1. 899 - ohne Topic (POF3-899) (POF3-899)

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